<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>div</title>
    <style type="text/css">
        .box1{
            width: 280px;
            height: 280px;
            background: red;
            padding-bottom: 10px;
            /*top left right bottom*/
            border-top: 10px solid blue;
            margin: 10px;
        }
        .box2{
            width: 280px;
            height: 280px;
            background: red;
            padding-bottom: 10px;
            /*top left right bottom*/
            border-top: 10px solid blue;
            /*margin-top: 20px;*/
            margin: 10px 20px 30px 40px;
            overflow: hidden;
        }
    </style>
</head>
<body>
   <!--  <div class="box1">
      学并思1 
    </div> -->
    <div class="box2">
      学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思2学并思
    </div>
</body>
</html>